Jan Vermeulen

Verbal memory decline after temporal epilepsy surgery?: A 6-year multiple assessments follow-up study.

Objective: To assess the long-term effects of temporal lobe epilepsy surgery on verbal memory. Methods: We assessed verbal memory performance as measured by a verbal learning test (“15 Words Test,” a Dutch adaptation of Reys Auditory Verbal Learning Test) before surgery and at three specific times after surgery: 6 months, 2 years, and 6 years in 85 patients (34 left temporal lobe [LTL] vs. 51 right temporal lobe [RTL]). An amygdalo-hippocampectomy and a neocortical temporal resection between 2.5 and 8 cm were carried out in all patients. Results: LTL patients showed an ongoing memory decline for consolidation and acquisition of verbal material (both 2/3 SDs) for up to 2 years after surgery. RTL patients at first showed a gain in both memory acquisition and consolidation, which vanished in the long term. Breaking the group up into a mesiotemporal (MTS) group and a non-MTS group showed clear differences. The group with pure MTS showed an overall lower verbal memory performance than the group without pure MTS, in the LTL group more pronounced than in the RTL group. After surgery, both pathology groups showed an ongoing decline for up to 2 years, but the degree of decline was greater for the LTL patients with MTS compared with the non-MTS group. Becoming and remaining seizure-free after surgery does not result in a better performance in the long term. Predictors of postoperative verbal memory performance at 6 years after surgery were side of surgery, preoperative memory score, and age. Conclusions: The results provide evidence for a dynamic decline of verbal memory functions up to 2 years after left temporal lobectomy, which then levels off.

The Wada test: prediction of focus lateralization by asymmetric and symmetric recall

PURPOSE The intracarotid amytal test is commonly used as a predictor of memory dysfunctioning after anterior temporal lobe resection (ATL) for intractable epilepsy. Asymmetry in memory scores can provide focus lateralizing information. In this study the predictive value of a set of Wada test parameters was analyzed, including patients with symmetrical memory scores. METHODS The Wada test was carried out in 226 patients undergoing ATL (94 L, 132 R). Data were collected on item recognition (five items), story recall, amytal dose, presentation time, EEG and arterial filling of amytal. A logistic regression analysis was performed on these data in order to find a set of variables which could best predict the side of seizure onset. RESULTS The analysis yielded four variables, i.e. both memory scores, story recall after right-sided injection and presentation time of stimuli after left-sided injection which could correctly predict seizure lateralization in 85% of the cases. Misclassification was lower for right foci than for left foci. Seizure outcome was four times more favourable in the correctly classified patients. CONCLUSIONS The results suggest that prediction of focus lateralization in temporal lobe epilepsy can be fairly exact even if left/right memory scores are equal. Performing the Wada test with only five memory items keeps the time window of active amytal short enough and gives accurate information about contralateral temporal lobe functioning. The classification scheme can be useful in predicting a lowered chance of seizure freedom.

Language activation distributions revealed by fMRI in post-operative epilepsy patients: Differences between left- and right-sided resections

OBJECTIVE To reveal differences of cerebral activation related to language functions in post-operative temporal lobe epilepsy (TLE) patients. METHODS Right (RTL) and left temporal lobe (LTL) resected patients, and healthy controls were studied using functional magnetic resonance imaging (fMRI). Only patients with complete left-hemispheric language dominance according to the intracarotid amytal procedure (IAP) were included. Language-related activations were evoked by performing word generation and text reading language tasks. Activation lateralization and temporo-frontal distribution effects were analysed. RESULTS For word generation, only LTL patients showed reduced left lateralized activation compared to controls, due to a decrease in activation in the left prefrontal cortex and an increase in the right prefrontal cortex. For reading, the left-hemispheric lateralization in RTL patients increased because of enhanced activity in the left prefrontal cortex, whereas for LTL patients the activation became bilaterally distributed over the temporal lobes. Lateralization results between pre-operative IAP and post-operative fMRI were highly discordant. Significant temporo-frontal distribution changes manifested from the reading but not from the word generation task. CONCLUSION The cerebral language representation in post-operative LTL epilepsy patients is more bi-hemispherically lateralized than in controls and RTL patients. Post-operative temporo-frontal and interhemispheric redistribution effects, involving contralateral homologous brain areas, are suggested to contribute to the cerebral reorganisation of language function.

Long-term effects of temporal lobectomy on intelligence.

Objective: To characterize the long-term effects of anterior temporal resection on intelligence. Methods: Twenty-eight left temporal lobectomy (LTL) and 43 right temporal lobectomy (RTL) patients were followed at standard time points for at least 6 years after surgery. Results: The average gain 6 years after operation was 3.6 Verbal IQ (VIQ) points and 10.3 Performance IQ (PIQ) points in LTL patients and 2.9 VIQ points and 7.7 PIQ points in RTL patients. A seizure-free outcome did not influence the increase in IQ, nor was the extent of resection related to IQ scores at the 6-year follow-up. Patients with exclusively mesial temporal sclerosis did not perform as well as patients with other pathologies, both before and after surgery. Major predictors of improved performance at 6 years were initial higher level of performance and lower age at surgery. Much of the observed improvement may be related to retest effects. Conclusions: The effects of epilepsy surgery on intelligence in the long term are limited. The largest gain in VIQ is seen from 2 to 6 years after surgery.

Usefulness of language and memory testing during intracarotid amobarbital testing: observations from an fMRI study

Background – Several procedures for testing language lateralization and memory function exist during the intracarotid amobarbital test (IAT). The use of functional magnetic resonance imaging (fMRI) gives the opportunity to assess the validity of some of these procedures, or at least to inspect the neuronal correlates. A comprehensive fMRI protocol was tested, aimed at addressing aspects of lateralization of language, as well as testing memory in relation to activation of mesiotemporal regions. Here we report observations with possible consequences for the current IAT procedures.

The Effects on Cognitive Performance of Tailored Resection in Surgery for Nonlesional Mesiotemporal Lobe Epilepsy

Summary:  Purpose: Mesiotemporal lobe epilepsy (MTLE) can be treated with different surgical approaches. In tailored resections, neocortex is removed beyond “standard” margins when spikes are present in the electrocorticogram. We hypothesized that these larger resections are justified because spiking neocortex is dysfunctional. This would imply that in patients with spikes (a) postoperative cognitive performance is not affected, and (b) preoperative performance is worse than without spikes.

Cognitive performance in learning disabled children with and without epilepsy

Cognitive functioning and educational achievement were examined in learning disabled children with epilepsy (n = 65) and without epilepsy (n = 122) in order to explore whether children with epilepsy show unique types of learning problems, different from those in other learning disabled children. The learning disabled children with epilepsy tended to perform better on tests of verbal intelligence, certain achievement-related abilities and were better in one area of academic achievement, i.e. spelling. Despite their superior performance in these areas, the learning disabled children with epilepsy were slower than those without epilepsy and regular education controls (n = 100) on simple auditory and visual reaction tasks as well as on a multiple decision reaction task and a visual searching task. The results obtained with the school achievement tasks provide no clear evidence for specific types of learning impairment in children with epilepsy. Learning disabled children with epilepsy do not appear to have educational needs different from those of other learning disabled children.

Lessons for neuropsychology from functional MRI in patients with epilepsy

This contribution aims to review the major findings of pre- and postsurgical functional magnetic resonance imaging (fMRI) in patients with refractory epilepsy from a neuropsychological perspective. We compared the contribution of fMRI with the intracarotid amytal procedure (IAP) with respect to functional mapping of language and memory in patients with therapy-resistant epilepsy. We conclude that using comprehensive language paradigms, fMRI has been able (1) to provide estimates of the degree of language lateralization including the degree of involvement of the nondominant hemisphere, (2) to provide information on the location of its activated network during expressive and receptive language, and (3) to help delineate eloquent language regions in the vicinity of the surgical target, thus preventing postoperative complications. The contribution of the frequently observed nondominant hemisphere activation to language should be explored and its clinical relevance determined. Evidence from fMRI studies is accumulating that reorganization of cognitive and motor function favors the activation of contralateral homotopic areas, although this process is far from understood. The exact functional contribution of atypical areas of activation should be investigated critically. In the presurgical evaluation process, detailed and reliable localization of language and memory functions of the individual patient is mandatory and should be the ultimate goal in the development of comprehensive clinical fMRI protocols.

γ-Vinyl GABA (Vigabatrin) and Mood Disturbances

Summary: We explored factors that may predispose patients to adverse mood effects during treatment with vigabatrin (γ‐vinyl GABA; VGB): mood disorders before VGB treatment, type of epilepsy, seizure type and seizure frequency, type and number of comedication, and VGB dose. The clinical relevance of such a study is that it may help identify circumstances in which VGB should be administered with caution. Seventy‐three patients (40 males, 33 females), all with refractory epilepsies, who received VGB as add‐on therapy, were assessed by the Amsterdamse Stemmingslyst (ASL), a mood‐rating scale, before the start of treatment, and demographic and clinical data were recorded. The patients were followed for 6 months after the start of VGB treatment. Treatment with VGB had to be discontinued in 38 patients (52% of the total sample). Mood problems were the main reason for discontinuation in 9 (12·3% of the total sample). In 6 other patients, mood problems were mentioned as the reason for discontinuing treatment, in combination with lack of drug efficacy. Development of adverse mood effects could not be predicted by a specific mood profile on the ASL. Before treatment, the “mood problems discontinuation group” did not show extreme scores for any assessed areas of mood and no significant differences from other patients were noted on the mood scales. Neither did clinical or demographic data show statistically confirmed specific characteristics for the mood problems discontinuation group, though the patients tended to use more antiepileptic drugs (AEDs) as cotherapy, to have a slightly lower daily dose of VGB, to be slightly older, and were mostly female. Especially the trend toward a relation with AED as comedication deserves further study.

Lateralization of auditory rhythm length in temporal lobe lesions.

In the visual modality, short rhythmic stimuli have been proven to be better processed (sequentially) by the left hemisphere, while longer rhythms appear to be better (holistically) processed by the right hemisphere. This study was set up to see if the same holds in the auditory modality. The rhythm task as originally designed by Seashore was computerized and is part of the Fepsy Neuropsychological battery. This task was performed by 85 patients with intractable temporal lobe epilepsy (left TLE = 32; right TLE = 53) enrolled in the Dutch Collaborative Epilepsy Surgery Program. They performed the task before and 6 months after surgery. The task consists of 30 pairs of rhythmic patterns in 3 series of 10 items. The series contains patterns of 5, 6, or 7 notes. The purpose is to indicate whether the two patterns are the same or different. Reaction times are also measured. If the hypothesis is true, the short-item sequence will be better processed by patients with right temporal lobe epilepsy (nonimpaired left temporal lobe), the longer sequence will be better processed by the left temporal epilepsy group (nonimpaired right temporal lobe). No overall laterality effect on rhythm perception could be found and no difference was found between both test moments. IQ did not correlate with rhythm performance. However, there was an interaction effect of laterality and rhythm length on performance and reaction time. This effect can be explained by the increase after the operation of the score of the left focus group and a decrease in the right focus group on the longer rhythms. This effect was somewhat less strong in the reaction times: a clear tendency for faster reaction times after surgery in the left and longer reaction times in the right focus group. The effect could not be explained for by the difference in extent of resection in either temporal lobe. This study showed that memory for and discrimination of auditory rhythm is dependent on which hemisphere is used in processing. The effect could be demonstrated for the right hemisphere, which uses a holistic processing of stimuli, which outperforms the left in rhythms consisting of a long sequence. In left temporal resections an improvement occurs on the longer rhythms and in right temporal resections the performance on the longest rhythms decreases.